Cytotypes of Andropogon gerardii Vitman (Poaceae): fertility and reproduction of aneuploids

Norrmann, Guillermo Alberto; Keeler, Kathleen H.

doi:10.1046/j.1095-8339.2003.00116.x

Cited by 18 publications

(20 citation statements)

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“…In wild populations of both species, pedicellate spikelets often mature and shed pollen before the stigmas of the sessile spikelets have become receptive (J. Hodge, personal observation), presumably serving as a mechanism to reduce self-pollination. Andropogon gerardi is known to be self-incompatible (Norrmann and Keeler 2003).…”

Section: Discussionmentioning

confidence: 99%

Patterns of Inflorescence Development of Three Prairie Grasses (Andropogoneae, Poaceae)

Hodge

Kellogg

2014

International Journal of Plant Sciences

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Editor: Félix ForestPremise of research. The tribe Andropogoneae (Poaceae) is a morphologically diverse clade that is distributed worldwide; members of the tribe are ecological dominants in some of the world's most expansive grasslands. Inflorescence morphology in the tribe is variable and does not indicate relationship, creating problems for systematic treatments of morphological characters. Closely related taxa may have different pollination syndromes and ecological roles, correlating with substantially different morphology. Methodology.To determine when morphological differences arise in developmental time, we investigated three species endemic to North American tallgrass prairies: big bluestem (Andropogon gerardi), little bluestem (Schizachyrium scoparium), and the inbreeding broomsedge bluestem (Andropogon virginicus). These species are widespread, common, and often ecologically dominant, but their development has never been studied. We used SEM to sample inflorescences from initiation to anthesis.Pivotal results. Both early and late development differ among the three species. Despite the close phylogenetic relationship of the two Andropogon species, many aspects of their development differed from each other and from those of Schizachyrium. Early in development, A. gerardi forms two long branches, A. virginicus forms one, and Schizachyrium does not form any. Andropogon gerardi and S. scoparium form similar trichomes and awns, whereas both structures are larger and more prominent in A. virginicus. The former two species develop three anthers per fertile flower, whereas the latter forms only one. In contrast, formation of spikelet pairs during middevelopment was quite similar among all three species.Conclusions. Differences among the three species appear early and continue throughout development. Only spikelet pair formation is shared among all three species. Developmental patterns do not reflect phylogeny, and early developmental events are not more similar among the two species of Andropogon.

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Section: Discussionmentioning

confidence: 99%

Patterns of Inflorescence Development of Three Prairie Grasses (Andropogoneae, Poaceae)

Hodge

Kellogg

2014

International Journal of Plant Sciences

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“…In addition, the tendency to produce unreduced gametes is not necessarily shared among closely related species. For example, Norrmann and Keeler (2003) report evidence for an unreduced egg cell from Andropogon lateralis, but found no evidence for unreduced gametes in over 1000 plants of A. gerardii.…”

Section: Asexual Reproductionmentioning

confidence: 93%

“…In most cases the offspring were sterile, but exceptions occurred, particularly among polyploid species. For example, Norrmann and Keeler (2003) report production of viable hybrids between Andropogon gerardii and A. lateralis, A. gerardii and A. glaucophyllus, and A. hypogynus and A. lateralis. The parents of these hybrids differ in chromosome number, but are all high polyploid (2n ¼ 60 and above).…”

Section: Barriers To Interspecific Crossingmentioning

confidence: 96%

“…The selfincompatibility response appears to require an interaction between the tip of the pollen tube and the stigma, so occurs after pollen germination (Heslop-Harrison and Heslop-Harrison 1987). Barriers to self-pollination may occur quite rapidly (within 90 seconds in Secale cereale; Heslop-Harrison 1982) or much later after the pollen tube has grown into the style -e.g., in Alopecurus pratensis (Shivanna et al (1982) and Andropogon species (Norrmann and Keeler 2003).…”

Section: Self-pollination and Self-incompatibility Systemsmentioning

confidence: 99%

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Reproductive Systems

Kellogg¹

2015

Flowering Plants. Monocots

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Reproductive systems in the grasses are diverse. This section begins by describing the morphological variation in placement of the stamens and pistils, and then follows with discussion of outcrossing, self-pollination and apomixis. UNISEXUAL VS. BISEXUAL FLOWERSGrasses may have unisexual or bisexual flowers. Because of the distribution of the unisexual versus bisexual condition in the immediate outgroups and early diverging taxa, attempts to determine the ancestral condition for the family are highly sensitive to analytical method and assumptions (Malcomber and Kellogg 2006). Among the graminid Poales, flowers of Flagellariaceae are bisexual, whereas those of Restionaceae, Centrolepidaceae and Anarthriaceae are unisexual. The two immediate outgroups of the grasses, Ecdeiocoleaceae and Joinvilleaceae, have unisexual and bisexual flowers, respectively. In the grasses, flowers in Anomochlooideae are bisexual, but those in Pharoideae are unisexual, and Puelioideae are bisexual. This distribution of character states indicates either that unisexual flowers have arisen repeatedly, or that reversion from unisexual to bisexual is fairly easy over evolutionary time, or both.Virtually all possible arrangements of unisexual flowers on the plant are known in the grasses (Connor 1981(Connor , 1987. Monoecy is widespread, appearing in all Pharoideae, tribe Olyreae of Bambusoideae, many members of Chloridoideae and Panicoideae, and some Ehrhartoideae. Among monoecious grasses, sex expression may vary between flowers within a spikelet (e.g., Lecomtella, Ixophorus), between spikelets within an inflorescence (e.g., Pharus, Hypogynium, Zizania), or between inflorescences within a plant (e. g., Zea, many Olyreae).Andromonoecy is common, particularly in the Panicoideae, in which spikelets are conventionally two-flowered, with the lower flower often producing stamens and the upper one being bisexual. Additional variations on this theme occur in the tribe Andropogoneae, with sex expression varying between the flowers in each of the two spikelets of the spikelet pair. For example, in many species of Andropogon, the sessile spikelet has a sterile lower flower and bisexual upper flower, while the pedicellate spikelet has a sterile lower flower and staminate upper one; this produces an inflorescence of bisexual and staminate flowers in a 1:1 ratio. In other Andropogoneae (e.g., Elymandra), the most proximal spikelet pairs on the inflorescence consist entirely of staminate flowers, thus increasing the ratio of staminate to bisexual flowers.In contrast to andromonoecy, gynomonoecy is rare in the grasses as a whole. Connor (1981) reports only eight genera with this distribution of flower types. In two of these, the bambusoids Diandrolyra and Piresia, the apparently bisexual flowers are in fact staminate with the gynoecium non-functional; thus, the plants are actually monoecious. In the chloridoid genus Munroa, pistillate flowers are proximal to bisexual ones in the spikelets of most species, but in M. squarrosa, pistillate spikelets occur only...

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“…Unlike switchgrass, in which the cytotypes are genetically isolated from one another (Martínez-Reyna and Vogel 2002; see also Chapter 11), big bluestem cytotypes freely crosspollinate. This generates viable aneuploid individuals from the native hexa-and enneaploid populations (Norrmann et al 1997;Norrmann and Keeler 2003). Such pollen transfer indicates gene flow is occurring from each group, suggesting a single species.…”

Section: Genetics and Breedingmentioning

confidence: 99%